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Abstract: The structure–activity relationship (SAR) study of two chemotypes identified as inhibitors of the human NAD+-dependent 15-hydroxyprostaglandin dehydrogenase (HPGD, 15-PGDH) was conducted. Top compounds from both series displayed potent inhibition (IC50 <50nM), demonstrate excellent selectivity towards HPGD and potently induce PGE2 production in A549 lung cancer and LNCaP prostate cancer cells. [Copyright &y& Elsevier]

An efficient and versatile Compound Management operation is essential for the success of all downstream processes in high-throughput screening (HTS) and small molecule lead development. Staff, equipment, and processes need to be not only reliable, but remain flexible and prepared to incorporate paradigm changes. In the present report, we describe a system and associated processes that enable handling of compounds for both screening and follow-up purposes at the NIH Chemical Genomics Center (NCGC), a recently established HTS and probe development center within the Molecular Libraries Initiative of the NIH Roadmap. Our screening process, termed quantitative HTS (qHTS), involves assaying the complete compound library, currently containing >200,000 members, at a series of dilutions to construct a full concentration–response profile. As such, Compound Management at the NCGC has been uniquely tasked to prepare, store, register, and track a vertically developed plate dilution series (i.e., inter-plate titrations) in the 384-well format. These are compressed into a series of 1536-well plates and are registered to track all subsequent plate storage. Here, we present details on the selection of equipment to enable automated, reliable, and parallel compound manipulation in 384- and 1536-well formats, protocols for preparation of inter-plate dilution series for qHTS, as well as qHTS-specific processes and issues. [Copyright &y& Elsevier]

Endoplasmic reticulum (ER) dysregulation is associated with pathologies including neurodegenerative, muscular, and diabetic conditions. Depletion of ER calcium can lead to the loss of resident proteins in a process termed exodosis. To identify compounds that attenuate the redistribution of ER proteins under pathological conditions, we performed a quantitative high-throughput screen using the Gaussia luciferase (GLuc)-secreted ER calcium modulated protein (SERCaMP) assay, which monitors secretion of ER-resident proteins triggered by calcium depletion. We identify several clinically used drugs, including bromocriptine, and further characterize them using assays to measure effects on ER calcium, ER stress, and ER exodosis. Bromocriptine elicits protective effects in cell-based models of exodosis as well as in vivo models of stroke and diabetes. Bromocriptine analogs with reduced dopamine receptor activity retain similar efficacy in stabilizing the ER proteome, indicating a non-canonical mechanism of action. This study describes a strategic approach to identify small-molecule drugs capable of improving ER proteostasis in human disease conditions. [Display omitted] • High-throughput screening identifies stabilizers of the resident ER proteome • Several FDA-approved drugs stabilize the ER proteome during ER calcium depletion • Bromocriptine is a top hit and does not act through dopamine receptors • Bromocriptine is efficacious in disease models associated with calcium dysfunction Depletion of endoplasmic reticulum (ER) calcium can lead to the loss of resident proteins in a process termed exodosis. Henderson et al. performed a high-throughput screen for compounds that attenuate exodosis and identify clinically approved drugs, including bromocriptine. Bromocriptine elicits protective effects in models of ER dysregulation, including stroke and diabetes. [ABSTRACT FROM AUTHOR]

An abstract of the article "Fluorescent Protein-Based Cellular Assays Analyzed by Laser-Scanning Microplate Cytometry in 1536-Well Plate Format," by Douglas S. Auld and colleagues is presented.

Proliferating cells, including cancer cells, obtain serine both exogenously and via the metabolism of glucose. By catalyzing the first, rate-limiting step in the synthesis of serine from glucose, phosphoglycerate dehydrogenase (PHGDH) controls flux through the biosynthetic pathway for this important amino acid and represents a putative target in oncology. To discover inhibitors of PHGDH, a coupled biochemical assay was developed and optimized to enable high-throughput screening for inhibitors of human PHGDH. Feedback inhibition was minimized by coupling PHGDH activity to two downstream enzymes (PSAT1 and PSPH), providing a marked improvement in enzymatic turnover. Further coupling of NADH to a diaphorase/resazurin system enabled a red-shifted detection readout, minimizing interference due to compound autofluorescence. With this protocol, over 400,000 small molecules were screened for PHGDH inhibition, and following hit validation and triage work, a piperazine-1-thiourea was identified. Following rounds of medicinal chemistry and SAR exploration, two probes (NCT-502 and NCT-503) were identified. These molecules demonstrated improved target activity and encouraging ADME properties, enabling in vitro assessment of the biological importance of PHGDH, and its role in the fate of serine in PHGDH-dependent cancer cells. This manuscript reports the assay development and medicinal chemistry leading to the development of NCT-502 and -503 reported in Pacold et al. (2016). [ABSTRACT FROM AUTHOR]

Abstract: Introduction: : The arrhythmogenic risk of fluoxetine, citalopram, and venlafaxine were evaluated through preclinical assays measuring hERG, blood pressure and electrical alternans over their respective clinical unbound concentration ranges. Methods:Anesthetized guinea pigs were instrumented with jugular and carotid cannulae for drug infusion and blood pressure monitoring respectively; a thoracotomy was performed for placement of a monophasic action potential probe on the left ventricle and for placement of pacing wires on the left ventricular apex. Drugs were infused as a 5-min loading dose immediately followed by a 10-min maintenance dose to achieve clinically relevant plasma concentrations; blood samples were taken at the end of each maintenance dose. Ventricular pacing was performed twice at baseline and at each dose level as follows: 50 preconditioning-beats at S1=220 (or 240) ms immediately followed by 30 test-beats at S2=200 ms. This S1–S2 protocol was repeated for S2=190 to 140 ms. HERG and calcium current measurements were recorded in HEK-293 cells stably expressing hERG potassium currents and freshly isolated guinea pig cardiac myocytes using the whole-cell configuration of the patch clamp technique. Results:Physiologically relevant inhibition (IC20) of hERG occurred at concentrations 22-fold (fluoxetine), 9-fold (citalopram), and 11-fold (venlafaxine) beyond their respective clinically effective concentration (C eff). At the highest achievable levels, fluoxetine (20-fold C eff) and citalopram (28-fold C eff) significantly decreased heart rate and/or blood pressure as well as increasing electrical alternans by 5 and 18 ms respectively. Venlafaxine increased blood pressure at only 1.3-fold C eff, but did not increase electrical alternans at the highest achievable dose (3.1-fold C eff). Discussion:These data suggest that evaluating other dose limiting side effects in relation to a drug''s therapeutic range may be crucial for accurate assessment of arrhythmia liability. [Copyright &y& Elsevier]

[Display omitted] Human epithelial 15-lipoxygenase-2 (h15-LOX-2, ALOX15B) is expressed in many tissues and has been implicated in atherosclerosis, cystic fibrosis and ferroptosis. However, there are few reported potent/selective inhibitors that are active ex vivo. In the current work, we report newly discovered molecules that are more potent and structurally distinct from our previous inhibitors, MLS000545091 and MLS000536924 (Jameson et al, PLoS One, 2014, 9, e104094), in that they contain a central imidazole ring, which is substituted at the 1-position with a phenyl moiety and with a benzylthio moiety at the 2-position. The initial three molecules were mixed-type, non-reductive inhibitors, with IC 50 values of 0.34 ± 0.05 μM for MLS000327069 , 0.53 ± 0.04 μM for MLS000327186 and 0.87 ± 0.06 μM for MLS000327206 and greater than 50-fold selectivity versus h5-LOX, h12-LOX, h15-LOX-1, COX-1 and COX-2. A small set of focused analogs was synthesized to demonstrate the validity of the hits. In addition, a binding model was developed for the three imidazole inhibitors based on computational docking and a co-structure of h15-LOX-2 with MLS000536924. Hydrogen/deuterium exchange (HDX) results indicate a similar binding mode between MLS000536924 and MLS000327069, however, the latter restricts protein motion of helix-α2 more, consistent with its greater potency. Given these results, we designed, docked, and synthesized novel inhibitors of the imidazole scaffold and confirmed our binding mode hypothesis. Importantly, four of the five inhibitors mentioned above are active in an h15-LOX-2/HEK293 cell assay and thus they could be important tool compounds in gaining a better understanding of h15-LOX-2′s role in human biology. As such, a suite of similar pharmacophores that target h15-LOX-2 both in vitro and ex vivo are presented in the hope of developing them as therapeutic agents. [ABSTRACT FROM AUTHOR]